DESCRIPTION: (Adapted from the Applicant's Description) Infertility affects over 90 percent of men with spinal cord injury (SCI). The defining characteristic of this poorly understood condition is an unusual semen profile showing normal sperm concentration and extremely impaired sperm motility and viability. Current knowledge of the effects of SCI on the physiology of the reproductive system is meager. SCI men s seminal plasma has been shown to inhibit sperm motility in both SCI and non-injured men. Whether the sperm of men with SCI is normal before their exposure to the seminal plasma is unknown. The long-term objective of this project is to determine the cause(s) of poor sperm motility and viability in men with SCI. The specific aim of this pilot project is to determine if the poor sperm motility and viability of men with SCI originates with the seminal plasma. This will be done by testing the hypothesis that the sperm of men with SCI are normal before they mix with seminal plasma. Research Design: Ten men with SCI and ten able-bodied men will comprise the study group. Pre-ejaculated sperm obtained by aspiration of the vas deferens will be compared to ejaculated sperm in each subject. These will be examined to: (1) Determine if the motility and viability of sperm from the vas deferens of men with SCI are the same as that of able-bodied men. (2) In SCI men, determine if their vas-aspirated sperm motility and viability are different from their ejaculated sperm motility and viability. (3) In able-bodied men, determine if their vas-aspirated sperm motility and viability are different from their ejaculated sperm motility and viability. The results of this study are expected to provide insight into the cause of poor sperm motility and viability in men with SCI and specifically, into the contribution of the seminal plasma in this condition. The results will then be used to generate strategies for further studies of the mechanisms involved in this condition, which should lead ultimately to improved treatments for poor semen quality in men with SCI.